title: Structure-activity-relationship studies around the 2-amino group and pyridine core of antimalarial 3,5-diarylaminopyridines lead to a novel series of pyrazine analogues with oral in vivo activity.
abstract: Replacement of the pyridine core of antimalarial 3,5-diaryl-2-aminopyridines led to the identification of a novel series of pyrazine analogues with potent oral antimalarial activity. However, other changes to the pyridine core and replacement or substitution of the 2-amino group led to loss of antimalarial activity. The 3,5-diaryl-2-aminopyrazine series showed impressive in vitro antiplasmodial activity against the K1 (multidrug resistant) and NF54 (sensitive) strains of Plasmodium falciparum in the nanomolar IC50 range of 6-94 nM while also demonstrating good in vitro metabolic stability in human liver microsomes. In the Plasmodium berghei mouse model, this series generally exhibited good efficacy at low oral doses. One of the frontrunner compounds, 4, displayed potent in vitro antiplasmodial activity with IC50 values of 8.4 and 10 nM against the K1 and NF54 strains, respectively. When evaluated in P. berghei -infected mice, compound 4 was completely curative at an oral dose of 4 × 10 mg/kg.
authors.affiliation: Department of Chemistry, University of Cape Town , Rondebosch 7701, South Africa.
authors.forename: Yassir
authors.initials: Y
authors.lastname: Younis
authors.forename: Frederic
authors.initials: F
authors.lastname: Douelle
authors.forename: Diego
authors.initials: D
authors.lastname: González Cabrera
authors.forename: Claire
authors.initials: C
authors.lastname: Le Manach
authors.forename: Aloysius T
authors.initials: AT
authors.lastname: Nchinda
authors.forename: Tanya
authors.initials: T
authors.lastname: Paquet
authors.forename: Leslie J
authors.initials: LJ
authors.lastname: Street
authors.forename: Karen L
authors.initials: KL
authors.lastname: White
authors.forename: K Mohammed
authors.initials: KM
authors.lastname: Zabiulla
authors.forename: Jayan T
authors.initials: JT
authors.lastname: Joseph
authors.forename: Sridevi
authors.initials: S
authors.lastname: Bashyam
authors.forename: David
authors.initials: D
authors.lastname: Waterson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Witty
authors.forename: Sergio
authors.initials: S
authors.lastname: Wittlin
authors.forename: Susan A
authors.initials: SA
authors.lastname: Charman
authors.forename: Kelly
authors.initials: K
authors.lastname: Chibale
mesh_terms: D000284:Administration, Oral; D000631:Aminopyridines / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D000962:Antimalarials / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D016466:CHO Cells; D003412:Cricetulus; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006801:Humans; D051379:Mice; D008862:Microsomes, Liver / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D021261:Parasitic Sensitivity Tests; D010962:Plasmodium berghei / Q000187:drug effects*; D010963:Plasmodium falciparum / Q000187:drug effects*; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D000631:Aminopyridines; D000962:Antimalarials